Transepidermal water loss (TEWL) is considered to be an indicator of the functional state of the cutaneous barrier (1-3). TEWL is believed to be related to irritant sensitivity and has been used to evaluate the clinical condition of the skin. Damage to the skin barrier from skin disease and physical or chemical trauma increases TEWL from an unperturbed baseline value. In addition,
From Skin Pharmacol Physiol 2005; 18:139, S. Karger AG, Basel.
TEWL is affected by environmental factors that include skin temperature, relative humidity of the air, occlusive factors, and mechanical abrasion. Physiological factors, such as cutaneous blood flow, stress, diurnal rhythm, eccrine and sweat gland density, and the thickness and composition of the stratum corneum, affect TEWL as well (4-10).
Vulvar irritant contact dermatitis is difficult to diagnose and irritation from sites used typically for measuring dermatitis (i.e., the forearm) are not predictive for the objective assessment of irritant dermatitis of the vulva (11-13). Previously, we sought to establish a standard procedure for assessing vulvar skin TEWL so that TEWL could be used as an indicator for the integrity and clinical status of vulvar skin.
Vulvar skin represents a unique dermatological region. For example, vulvar skin has a thinner stratum corneum than other skin (5); it can be considered at least semi-occluded (by virtue of garments and skin-on-skin contact) and naturally hydrated tissue (by virtue of garments, and abundance of eccrine and sweat glands, and its proximity to the vaginal orifice) (14,15). Under conditions of occlusion and hydration, TEWL cannot be measured effectively. In these situations, skin surface water loss (SSWL) over a period of time may be a more accurate indicator of the vulvar skin's integrity.
The measurement of vulvar SSWL is particularly challenging due to its semioccluded state and a location that is difficult to assess without causing stress to the individual. This, coupled with the vulva's richly innervated tissue and an abundance of eccrine and sweat glands, made the task of measuring SSWL quite ambitious (16). Previous reports showed that vulvar SSWL (in particular, the midpoint of the labia majora) is considerably greater than the forearm SSWL (15,16).
For this study, we compared the SSWL dynamics of the vulva and the inner thigh, sites that are partially occluded by garments, and for the inner thigh, a site that is closely apposed to the genital skin. We also assessed the influence of age, body-mass index (BMI), and atopy.
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